Worm-gearing.



Patented Apr."l7, |900.

E. a. Ho||-'MANNT wann Gamma.'

V (Applicmzion led. June 14, 1899.) (No Model.) 5 Sheets-Sheet L 5 fig.;

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No. '647,49l. Patented Apr. I7, |900.

E. e. HOFFMANN.

WORM HEARING.

(Applicltiun med. June 14, 1599.) (No Model.) 45 Sheets-Sheet 2` Fl'g;

WITNESSES.

No. 647,49l. PatenteqApr. I7, |900.

. E. G. HOFFMANN.

WORM HEARING.

` (Appucation filed June 14, 1899.) (No Model.) 5 Sheets-Sheet 3.

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Patented Apr. |7,'|900.

' E. G. HOFFMANN.

WORM GEARING.

(Application led June 14, 1899.)

5 Sheets-Sheet 4 (No Mod'eL WWA/5555.

Patented Apr. I7, |900.

E. .V HOFFMANN.

WRM GEARI NTTED STATES PATENT OFFICE.

ERNST GUSTAV HOFFMANN, OF CHELMSFORD, ENGLAND,

WORM-GEARING.

SPECIFICATION forming part of Letters Patent No. 647,491, dated April17, 1900.

Application filed June 14, 1899. Serial No. 720,474. (No model.)

T0 ct w/wm it may concern:

Be it known that I, ERNST GUsTAv HOFF- MANN, a subject of His Majestythe German Emperor, residing at Chelmsford, in the county of Essex,England,have invented a certain new and useful Improvement in Worm-Gearing, of which the following is a specification.

My invention relates to certain improvements in and connected withworm-gearing, the object of the saine lbeing to produce a practicalworm-gearing adapted by reason of itseasy running, absence of friction,and its great safety for various mechanical purposes, such as forelevator-work, where the use of a rack and worm is even safer than ahydraulic ram, by reason of the whole gearing being self locking orholding in anyposition, so long, of course, as the worm does not exceeda certain amount of incline.

According to one form of my invention the worm maybe of any usual orconvenient form,'

though the actual tooth is of a construction hereinafter described;butin place of employing teeth on the worm-wheehor, it may be, the rackas an equivalent thereof, I insert studs on the periphery of the wheel,either in line with the radius or in line with the aXis of the wheel, oron the face of the rack, and upon each' of said studs a ring-shapedroller having the outline of the tooth it substitutes revolves on aball-bearing. of a special construction. In the case of an elevator suchracks would be preferably ixed to the sides of the well and the worm orworms to the car-platform or to. some suitable part of the car, whichwould also carry a suitable motor, preferably electric, with shaftingand-gearing connecting it to the worm or worms to rotate same, and thusmove the car positively up or down, the arrangement enabling the gearingto be self-locking and permitting the car to be counterbalanced to theextent desired.

I also employ various other details in carrying out my invention, whichform an important feature of same and which will be claimed as part ofsame. v

In the accompanying drawings I illustrate various forms of my inventionand the manner of carrying it into effect.

In the drawings, Figure l is a section of a part of a worm and rack, theWorm being partlyin elevation. Fig. 2 is a sectional plan through therack and one of the roller-studs shown in Fig. l, the worin being viewedin elevation of Fig. 3, partly in section, on line 6o y y of saidligure, looking in the direction of the arrow. Fig. 5 is an elevation,on a larger scale than Figs. 3 and 4, of the rack-worm and a part ofcertain appliances connected thereto. in Fig. 5. Fig. 7 is amodiiication, being a side elevation of a worm-wheel engaging with aworm. Fig. 8 is a cross-section through line 0c, Fig. 7. Eig. 9 is asimilar View to Fig. 8, but showing a modification of the worm- Wheel.Fig. l0 is a plan view, partly in section, of a modified arrangementover that shown in Figs. 7 and 8, in which the worm is allowed a play ormovement; and Fig. 1l is an end view of same.

The gearing may consist of the ordinary form of worm; but I prefer touse the special form shown most, clearly in Figs. l and 5, `where itwill be seen that the ordinary bevwhich engages in the present case withthe rollers 3, are provided with a prolongation 4, which enters into theangularly arranged grooves-5 on the rack bar or base G--that is Fig. 6is a plan of the worm shown 65 leled faces l l of the tooth of the worm2, 8o

to say, the tooth is so extended diametrically that it enters the solidpart of the rack. These grooves or slots, however, have a margin ofspace on both sides of the tooth, so that the latter is not actually incontact with the rack,

the object of this extension or prolongation 9o of the tooth being toprovide a safety device whereof the tooth may actually engage with asolid rack in the event of one of the rollers breaking, althoughnormally the tooth is out of contact with this portion of the rack. Thisforms a safety device of considerable value where much depends upon theworm, as in the case where same is used in elevator-work.

IOO h abling liat, and therefore increased, contact surfaces to beemployed.

The rollers 3, as will be understood, replace the usual teeth of therack, each roller being ring-shaped and having the outline of the toothit substitutes. The ring or roller 3 is mounted on a ball-bearing of thekind known as a single-row four-track bearing. The head 7 of the stud 8,which holds the roller, is conical on its under side and forms a part ofthe ball-bearing cone, and adjoining it. is a movable double cone 9,fitting on the stud bya screw-thread 10, having, for instance, twentj)four threads per inch, while the end of the stud is also provided with ascrew-thread 11, which (with twenty-four threads on the first)preferably has only twenty threads per inch, this latter screwing intothe rack body or base 6. Between the outer face of the cone 9 and thecone-face of the head 7 is situated a row of balls 12, which bear on thedoubleconed face forming the interior of the ring or roller 3. The head7 of the stud projects from the outer face of the ring and is suitablyshaped to enable it to beheld by a wrench or tool, so that the stud maybe screwed into the rack. The inner face of the cone 9 seats in acorrespondingly shaped recess in the rack-base 6.' Y/lt will be seenthat in this way the stud may be screwed onto the base 6 from theoutside; but in the operation of an elevator service, for instance, itwill be appreciated that unless some device were provided to secure thestud the concussions would have a tendency to loosen it.

The device which I employ is the above-described arrangement of the twothreads, which are non-correspondin g in their pitch, together with, ifdesired, alocking device. `With such threads when screwing the stud intothe rack it will be obvious that the twenty-threads per-inch portionwill pull the stud into the rack faster than the twenty-fourthreads-perinch portion will allow it to pass through the cone 9, which is seatedin the rack-base, so that a slight straining is set up through thedifference between the two sm all threads,with

the result that a ver gradual tightening of the parts is produced, theoperation being practically the same as if a screw having one hundredand twenty threads per inch were employed, without the disadvantageswhich such a line thread as the latter would have. As a matter ofpractice it may be said that with this construction of twenty-four andtwenty threads per inch, respectively, one complete turn of the stud canbe given to same after the parts have just begun to tighten, and thisone complete turn shows to what extent the members have been strainedand jammed together. The incline of the threads being thus small, nodanger exists of the stud being loosened by concussions when the abovemethod is employed. To furthermore secure the stud, I employ a set-screw13, which passes through from the side of the rack-base G and isprovided with a conical ond 13, which bears tangentially against theplain portion of the stud 8 and jams the latter after it has beentightened up.

In applying the foregoing arrangement of parts to an elevator, as shownin Figs. 3 to 6, I preferably employ two oi the worms 2 and place thembeneath the platform let, driving them by means of an electric motor 15through a shaft 16 and couplings 17, the shaft 16n on the other side ofsaid couplings driving through bevel-wheels 18 18, Fig. 5, the worms 2.Each worm is carried on suitable bearings in a bracket 19, consisting ofa top part, a bottom part 19D, and two vertical connectingbars, saidbrackets having a third connecting-bar 19, which is bolted at 19c to theupper part of the bracket 19 at the top and carries the upper half 2O ofthe bearing for shaft 16a. The lower half 20 of the bearing is formed aspart of the bottom 1 9". By releasing the bolt 19c the bar 19TL can beremoved, together with the upper part 2() of the bearing, so that afterundoing the coupling 17 the part 1G of the shaft, with the bevel-wheel1S, can be removed, whereby the worm 2 can be reached for repair orremoval. To the bar 19 is pivoted at 21 lever 22, the yoke-shaped end ofwhich pivotally carries a cone-shaped ring or disk 23, which tits into acorrespondingly-shaped recess 23^pl in the upper part of the worin 2,one of such coned parts bearing a leather or other suitable facing. Thelever 22 may be operated in some suitable and wellknown way from the carand as will be seen may act on the coned part 23 to cause it to act as aclutch or brake or holding device for the worm, in which manner the wormproper becomes the means for stopping the car, the arrangement beingpreferable to applying a brake direct to the motor-shaft, as the worinis in direct and positive engagement with the rack.

The above-described arrangement of gearing, being absolut-elyself-locking, permits the car to be counterbalanced to any extentdesired, because the car can neither go up nor down, but can only movein the direction in which the worms drive it as said worms wind theirway either up or down the rack.

Then the worm is used in connection with a worm-wheel, it is preferableto mount the studs, with their rollers, on the side of the periphery ofthelwheel or at right angles to such periphery, as'the arrangementaffords greater facility for carrying the construction into effeet. Theadvantage of this ball-bearing and gearing is also very great when itbecomes necessary to-drive the worm instead of the worm-wheel. Suchgearingis frequently used where high speed is required, but no greatpower is to be transmitted except that wanted to create the speed. As atpresent constructed such gears require the worm to have a very rapidincline in order to make them work at all satisfactorily, whereas theangle of the ICO IIO

worm-thread can be much reduced when the present arrangement is employedin consequcnce of the friction between the worm and the worm-wheelteeth, which in this instance are the rollers, being reduced to mererolling friction as against a rubbing one in the ordinary construction.

In the construction shown in Figs. 7 and 8 the ball-bearing rollers 8are carried on the opposite side of a yoke-shaped portion 24a of theworin-wheel 24-that is to say, on the inside of such part Qta-andopposed to each other, this double construction enabling the dimensionsof the ball-bearing rollers forming the worm-wheel teeth, and naturallythe diameter of the worm, to be considerably reduced. The extension orsafety teeth 4c in this case I prefer to form on the worm-wheel 24,between the parts 24a, the teeth passing between the teeth l of the worm2, but not cngagin g with same unless through the breakage of some ofthe rollers. `The teeth 4, however, may be formed on the teeth l in thesame way as previously described and enter grooves in the parts 24between the rollers in the same way.

It is desirable where the rollers are duplicated, as in the aboveinstance, that necessarily the rollers on both sides should be in gearwith the worm, which might not be the case if the divisioning of thewheel in the setting of the rollers is at all faulty. To obviate this, Iemploy the arrangement shown in Fig. 9, where it will be seen that theWormwheel 2a is divided into two parts 24h and 24C, which are loose upontheir shaft 25, so that they are compensating, the play enabling theworm to bear equally on a roller on each side. The two parts 24h and 24Cdrive, through a number of pins 26, a Wheel 24d, placed between the twoparts 24J and 24; and fixed to the shaft 25, such pins 26 beingpivotally hung on studs 27 in slots 28, which studs are formed in thisinstance as screws passing from the periphery of the wheel 24d throughthe slots. In this way the pins, while serving to drive wheel 24J?, canyet rock sufficiently to enable the compensating movement to take placebetween the parts 24h 24C, or when the worm wheel is arrangedsubstantially as shown in Figs. 7 and 8 that is to say, is a'liXture--the worm may be allowed to be slightly movable laterally asbetween the two sets of rollers, so that should those on one side pressheavily against the worm the latter will yield sidewardly, and thusinsure an equal pressure on both sides. To accomplish this, variousconstructions could be used. For instance, the worm might be mounted ona shaft in a kind of ball-and-socket joint or on a slide which movessidewardly, in which event of course the worm would require to beattached to its shaft by a suitable coupling.

One arrangement which has been found suitable is shown in Figs. 10 andl1. In this the wormwheel 2 is provided with an opening through same,formed with outwardlyflaring mouths at each end, as shown at 30, thecurvature through the hole being that of the segment of a circle whichtouches the shaft only at the central point. The worm is capable ofrevolving with the shaft through a key 3l, secured to the shaft andengaging in slots 32, the arrangement enabling the worm to be drawn olfthe shaft. i The worm is provided, further, with a central boss portion,the ends of which are struck on the curve of a circle and whichcorrespond with abutments 3ft 34, having similar curved faces, one ofthese abutments being held against the boss portion of the worm by meansof nuts 35, engaging with a screwed portion ot' the shaft, which forcesthe other abutment against a fixed collar 3G. When the pressure of thenuts is properly adjusted, the worm will be able to rock slightly on theball-andsocket joint which is thus formed and so may adjust itself toinequalities of the other member.

l. In a worm-gearing and in combination with the worm forming onemember, a revoluble ring forming part ol' the other member, a doublecone-face on the inside of the ring, a stud for carrying the ringprovided with a head having a cone-face, a second adjustable cone-facecarried by the stud,and antifriction-balls between the conefaces of thestud and ring.

2. In a worm-gearin g, the combination with a roller forming a part ofone member thereof, a stud for holding same having separate threadedportions of a different pitch, a base into which one threaded portionscrews, and a threaded part carried by the base into which the secondthreaded portion screws whereby a straining or jamming is set up betweenthe two parts as the stud is screwed in.

3. In a worm-gearing and in combination, arevoluble roller forming apartof one member, a threaded stud for carrying same, abase forming afurther part of the same member, into which the stud is screwed, afurther threaded portion on the stud, the threads of which are of adifferent pitch to the rst threads, an adjustable part carried by suchfurther threaded portion and adapted to seat on the base whereby whenthe stud is screwed into the base astraining and jamming is setupbetween the part seating on the base and the threaded portion screwinginto the latter.

4f. In aworm-gearing, and in combination, a revoluble ring forming apart of one member, a threaded stud for carrying same, a coneshaped headon the stud, a base forming a further part of said member into which thestud is screwed, a further threaded portion on the stud the threads ofwhich are of a different pitch to the first threads, an adjustablecone-shaped part carried by the latter threaded portion and adapted toseat on the base, and antifriction-balls carried between this conedpart, the coned head, and the ring, the difference between the pitch ofthe threads causing astrainin g and jamming between the IOO TIO

iii

part seated on the base and the threaded portion screwing into thelatter when the stud is screwed in.

5. In a worin-gearing, the combination with arollerforming a part of onemember thereof, a stud for holding same, having separate threadedportions of a different pitch, a base into which the threaded portionscrews, a threaded part carried by the base into which the secondportion screws, whereby a straining and jamming is set up between thetwo parts as the stud is serewed in, and a set-screw having a eoniealhead screwing into the base and adapted to engage tangentially with thestud.

6. Ina worm-gearing, the combination with a Worm forming one memberthereof, of rollers forming apart of the other member thereof, and meanscarried by one of the members, and adapted to engage with the othermember, in the event of the rollers giving way.

7. In a worm-gearing, and in combination a Wormforming one memberthereof, having a tooth provided with a prolongation, and a base formingapart of the other member thereof, provided with grooves with which saidprolongation can engage in the ease of a breakage of a part forming therest of the member.

S. In a worm-gearing, the combination with rollers forming one memberthereof, a base for carrying same, and grooves on such base between saidrollers, of a Worm forming the other member, the tooth of said wormbeing prolonged to engage with said grooves in the event of the rollersgiving way.

9. In a worm-gearing, a worm forming one of the members of same, aworm-wheel forming the other member of same, two sets ofantifrietion-rollers oppositely arranged with which the worm engages,means for carrying the rollers, and means for equalizing the pressure onthe rollers on both sides of the Worm.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

ERNST GUSTAV HOFFMANN.,

